d_diameter
| CODE | DESCRIPTION | FROM_YEAR | TO_YEAR |
|---|---|---|---|
| 1 | Calliper in one direction | 1984 | |
| 2 | Calliper in two directions, one perpendicular to another | 1984 | |
| 3 | Diameter is average of 2 perpendicular calliper measurements | 1984 | |
| 4 | Diameter tape | 1984 | |
| 5 | Measuring tape | 1984 | |
| 6 | Diameter taken from girth bands | 1984 | |
| 7 | Diameter estimated | 1984 |